Zipcode-based classification

In recent years, interest has grown in parsing voters’ attitudes by their community’s degree of urbanicity or rurality. The Marquette Law Poll asks respondents, “Would you describe the place where you live as urban, suburban or rural?” If necessary, we clarify, “Urban is a big city like Milwaukee, Madison or Green Bay. Suburban is a built up place close to a big city and rural is less built up with fewer people and further away from a big city.”

This self-description is interesting, but it’s not entirely clear what it tells us. Each individual defines those terms in their own mind, and many places don’t fall neatly within the three offered categories.

Using the USDA Rural-Urban Commuting Area Codes (RUCA) I have created an alternative, objective zip-code based geography classification for the Marquette Law Poll. “Objective” does not mean “correct.” It simply means that the same data-based methodology has been uniformly applied to each case.

The original USDA RUCA classification is based on both a zip code’s location (e.g. within a census-defined urbanized area or urban cluster) as well as how its residents commute. Because it is a measure of economic activity, RUCA does not further distinguish between central cities and suburbs within metro areas. Obviously, the city-suburb distinction is crucial for political research, so I add a new principal city code. This consists of all zip codes with a majority of their population inside a metropolitan statistical area’s principal city (or cities).

With my addition of principal cities, here are all 11 RUCA categories along with the number of Wisconsin zip codes in each. I combine the 11 RUCA codes into 5-category, 4-category, and 3-category alternatives as indicated. The 5, 4, and 3-category RUCA breakdowns are available as crosstab variables on the Marquette Law Poll interactive crosstab web application.

zips ruca11 ruca5 ruca4 ruca3
65 Principal city Principal city Principal city Urban areas
106 Suburban core Suburban core Suburban core Urban areas
138 Strongly tied to urban area Exurbs and large towns Exurbs and large towns Exurbs and large towns
22 Weakly tied to urban area Exurbs and large towns Exurbs and large towns Exurbs and large towns
38 Large town Exurbs and large towns Exurbs and large towns Exurbs and large towns
44 Strongly tied to large town Exurbs and large towns Exurbs and large towns Exurbs and large towns
7 Weakly tied to large town Exurbs and large towns Exurbs and large towns Exurbs and large towns
71 Small town Small town Rural and small towns Rural and small towns
42 Strongly tied to small town Small town Rural and small towns Rural and small towns
16 Weakly tied to small town Small town Rural and small towns Rural and small towns
223 Isolated rural Isolated rural Rural and small towns Rural and small towns

Maps

Click through these tabs to view which zip codes make up each category, for each RUCA level.

RUCA 11

RUCA 5

RUCA 4

RUCA 3

Population

Use the tabs below to see the population of each RUCA category.

RUCA 11

Wisconsin population
pop pct
Principal city 1,836,003 32%
Suburban core 1,681,561 29%
Strongly tied to urban area 528,974 9%
Weakly tied to urban area 37,851 1%
Large town 558,304 10%
Strongly tied to large town 88,649 2%
Weakly tied to large town 9,897 0%
Small town 481,127 8%
Strongly tied to small town 83,657 1%
Weakly tied to small town 22,885 0%
Isolated rural 448,984 8%

RUCA 5

Wisconsin population
pop pct
Principal city 1,836,003 32%
Suburban core 1,681,561 29%
Exurbs and large towns 1,223,675 21%
Small town 587,669 10%
Isolated rural 448,984 8%

RUCA 4

Wisconsin population
pop pct
Principal city 1,836,003 32%
Suburban core 1,681,561 29%
Exurbs and large towns 1,223,675 21%
Rural and small towns 1,036,653 18%

RUCA 3

Wisconsin population
pop pct
Urban areas 3,517,564 61%
Exurbs and large towns 1,223,675 21%
Rural and small towns 1,036,653 18%

Data accuracy

The data underlying the USDA’s original 2010 RUCA codes is growing stale. Updated classifications will be available sometime after the 2020 census. Fortunately (for our purposes), Wisconsin’s population and economic patterns have changed very little this decade, with the important exception of the Madison metro area. I expect Madison’s footprint to expand significantly in the 2020 RUCA vintage. The rest of Wisconsin will probably look much the same.

RUCA vs self-reported geography

RUCA codes do not line up perfectly with self-reported urban, suburban, or rural status. The following tables show the self-reported geography by RUCA classification, for each level of RUCA.

It seems to me that respondents use a sort of “backporch” test to answer the urban/suburban/rural question. If the view from their house contains fields, they call it “rural.” The RUCA classification, on the other hand, is fundamentally an economic judgement. People who live in visually “rural” areas that are nonetheless economically intertwined with larger metros are considered part of a metro area.

RUCA 11

Self-reported geography vs. RUCA geography classification
Marquette Law School Poll, 2015-2020
Urban Suburban Rural Don't know n
Principal city 53% 35% 11% 1% 7,856
Suburban core 20% 59% 20% 1% 8,024
Strongly tied to urban area 8% 21% 70% 1% 2,539
Weakly tied to urban area 5% 10% 85% 0% 235
Large town 23% 30% 46% 1% 2,645
Strongly tied to large town 7% 10% 83% 0% 505
Weakly tied to large town 10% 4% 85% 2% 84
Small town 16% 14% 69% 1% 2,280
Strongly tied to small town 11% 8% 81% 0% 412
Weakly tied to small town 8% 10% 81% 2% 110
Isolated rural 7% 6% 85% 1% 2,345

RUCA 5

Self-reported geography vs. RUCA geography classification
Marquette Law School Poll, 2015-2020
Urban Suburban Rural Don't know n
Principal city 53% 35% 11% 1% 7,856
Suburban core 20% 59% 20% 1% 8,024
Exurbs and large towns 15% 23% 61% 1% 6,008
Small town 15% 13% 71% 1% 2,803
Isolated rural 7% 6% 85% 1% 2,345

RUCA 4

Self-reported geography vs. RUCA geography classification
Marquette Law School Poll, 2015-2020
Urban Suburban Rural Don't know n
Principal city 53% 35% 11% 1% 7,856
Suburban core 20% 59% 20% 1% 8,024
Exurbs and large towns 15% 23% 61% 1% 6,008
Rural and small towns 12% 10% 78% 1% 5,147

RUCA 3

Self-reported geography vs. RUCA geography classification
Marquette Law School Poll, 2015-2020
Urban Suburban Rural Don't know n
Urban areas 36% 47% 15% 1% 15,880
Exurbs and large towns 15% 23% 61% 1% 6,008
Rural and small towns 12% 10% 78% 1% 5,147

RUCA and issues

RUCA codes line up nicely with lifestyle questions that we expect to vary along the rural-urban continuum. For example, 48 percent of rural respondents are deer hunters, compared with 38 percent from small towns, 36 percent from exurbs and large towns, 22 percent from the suburbs, and 19 percent from principal cities.

Are you or any member of your household a deer hunter?
Marquette Law Poll of Wisconsin registered voters, fall 2019
Yes, respondent Yes, another household member Yes, both respondent and another household member No, nobody in household Don't know n
Principal city 14% 9% 5% 71% 1% 412
Suburban core 19% 12% 3% 65% 0% 456
Exurbs and large towns 23% 14% 13% 50% 0% 335
Small town 25% 11% 13% 51% 0% 151
Isolated rural 35% 12% 13% 41% 0% 132

 

Democratic strength is concentrated in principal cities, where they have a 26-point advantage over Republicans (including independents who lean to either party). Combining all polls taken after 2016, Republicans have a 8-point partisan identification advantage in the suburbs, an 11-point advantage in exurbs and large towns, a 10-point advantage in small towns, and a 16-point lead in isolated rural areas.

 

Party ID by RUCA code
Wisconsin registered voters, 2017-2020
Republican Independent Democrat n
Principal city 32% 9% 58% 4,748
Suburban core 50% 8% 42% 5,027
Exurbs and large towns 51% 8% 40% 3,709
Small town 50% 9% 40% 1,680
Isolated rural 52% 11% 36% 1,408

 

Donald Trump’s weakness in the suburbs is clear. Despite a 8-point Republican identification advantage in the suburbs, Trump leads Joe Biden by just 1 point among suburban voters when all 2020 polling is combined.

Trump does best with voters from isolated and rural areas, where he has a 15-point lead over Biden. He has an 7-point lead in exurbs and large towns, along with an 8-point lead in small towns.

 

Biden vs Trump by RUCA code
Wisconsin registered voters, all 2020 polls through September
Joe Biden Donald Trump n
Principal city 59% 30% 1,553
Suburban core 45% 46% 1,599
Exurbs and large towns 43% 50% 1,258
Small town 41% 49% 540
Isolated rural 39% 54% 435